Toner cartridges for laser printers, copiers and multi function devices are well known in the art. A typical toner cartridge is designed to be handled by non skilled users during replacement or clearing of paper jams. To protect the photosensitive drum during such handling operations a cover is employed which is normally open when the cartridge is in use and closes when the printer or copier is opened for maintenance. Such drum covers are disclosed in U.S. Pat. No. 4,462,677 and U.S. Pat. No. 4,470,689.
In most popular embodiments of toner cartridges, the drum cover is solid and swings on an arm to a retracted position outside the cartridge. There are exceptions to this architecture, for example, as disclosed in U.S. Pat. No. 5,231,453, where a flexible cover is caused to roll up when retracted; and U.S. Pat. No. 6,091,916 where a multi-plate or slatted cover is caused to retract to a position inside the cartridge casing.
In the more common system where the cover is a one-piece barrier moulded out of styrene or similar material, which when retracted or open swings to a position outside and slightly removed from the cartridge body, it has been found beneficial to utilise the cover to guide airflow around the cartridge. Such systems are disclosed in U.S. Pat. No. 5,878,304, U.S. Pat. No. 6,075,956 and U.S. Pat. No. 6,097,911.
Most printers and copiers are fitted with a fan to move air through the interior of the apparatus and around or through the constituent modules. As far as the toner cartridge is concerned this has the beneficial effect of removing unwanted ozone which is generated at the primary charge station; and also loose particles of paper fibre and toner powder. Commonly, a filter might be fitted inside the main apparatus to capture such waste particles. An example would be a mechanical filter coupled with an active carbon element to remove the particulate matter and reduce the ozone respectively from the ejected air. It has also been proposed in U.S. Pat. No. 4,540,268 to mount the ozone filter onto the toner cartridge itself.
Recently, there has been concern about toner particles entering the office atmosphere.
It is a general object of the present invention to overcome one or more of the disadvantages of the prior art, or at least to provide a useful alternative thereto. However, the invention aims more specifically, at least in its preferred form, to reduce the amount of particles present in the air ejected from the main apparatus.